"no org-babel-execute function for c" and "no-org-babel-execute function for c++"

Question

my emacs version is 24.3.1.

i understand i have to put the ob-C.el (available from here) in a path where Emacs can read it.

i first copy-pasted the code from that .el file to my .emacs file and restarted emacs. then i went to a C code block (within an org file) and tried to execute it (using C-c C-c). the minibuffer said 'no org-babel-execute function for C'. the same story played out with trying to execute a C++ code block. note that R and python evaluate perfectly from within my org files. the problems seems to be only with these compiled languages.

i then tried putting this ob-C.el inside the ~/.emacs.d directory to see if that helped matters. restarted emacs and checked. it didn't work.

then i tried putting it into a directory ~/.emacs.d/lisp and added the following lines to my .emacs file

(add-to-list 'load-path "~/.emacs.d/lisp/")
(load "ob-C.el")
(require 'ob-C)

after restarting emacs, evaluating the C or C++ code blocks from within an org file still doesn't work. i keep getting the same error "no org-babel-execute function for C" or "no org-babel-execute function for C++".

Update

i upgraded my emacs version to 24.5, deleted all the previous elpa and melpa subdirectories in my ~/.emacs.d directory. suspecting that it had to do with the order in which i placed my

(custom-set-variables

'(org-babel-load-languages
(quote
((emacs-lisp . t)
 (C . t)
 (css . t)
 (sh . t)
 (awk . t)
 (R . t))))

and

;; load the pathnames to custom lisp files
(add-to-list 'load-path "~/.emacs.d/lisp/")
(load "ob-C.el")
(require 'ob-C)

code blocks, i put the load "ob-C.el" before the org-babel-load-languages thing. i then executed the c++ code block multiple times. no luck.

then i removed everything (cleaned out the custom-set-variables block in the .emacs file) and now my .emacs file looks like

;; load the pathnames to custom lisp files
(add-to-list 'load-path "~/.emacs.d/lisp/")
(load "ob-C.el")
(require 'ob-C)

;; load the languages that are needed
(org-babel-do-load-languages
'org-babel-load-languages '((C . t)))

Its still not working.

The code that i am trying to evaluate in an orgmode buffer is :

#+BEGIN_SRC c
printf("Hello world");
#+END_SRC

My Messages buffer looks like this after restarting emacs and attempting to execute the above code block :

Loading /home/taeten/.emacs.d/lisp/ob-C.el (source)...done
Wrote /home/taeten/.emacs.d/.emacs.desktop.lock
Desktop: 1 frame, 0 buffers restored.
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit [2 times]
Making completion list... [3 times]
org-babel-execute-src-block: No org-babel-execute function for c! [5   
times]
Ignoring unknown mode `elisp-mode'
File local-variables error: (void-function elisp-mode)
byte-code: Beginning of buffer [6 times]
byte-code: Beginning of buffer

Answer 1

You really only need this bit in your init file:

(org-babel-do-load-languages
 'org-babel-load-languages '((C . t)))

Note it's a capital C. This enables Babel to process C, C++ and D source blocks.

Answer 2

It should be a capital 'C' not a lower case 'c' for the name of the source code block.

#+BEGIN_SRC C
#+END_SRC

After solving this independently, I noticed @syntaxError also posted this solution above in the comments for @wvxvw's answer. I am submitting it here as an answer because it might be hard to see in a comment on an answer.